US blames Iran for drone attacks on Saudi Aramco

US Secretary of State Mike Pompeo has blamed Iran for Saturday's drone attacks on Saudi oil facilities.

He dismissed a claim by Yemen's Iran-backed Houthi rebels that they had attacked the two facilities, run by state-owned company Aramco.

Iran's foreign minister accused Pompeo of "deceit".

Saudi Arabia's energy minister said the strikes had reduced crude oil production by 5.7 million barrels a day - about half the kingdom's output.

The main Saudi stock exchange plummeted 3% on opening on Sunday, before recovering.

Saturday's drone attacks hit Abqaiq, site of Aramco's largest oil processing plant, and the Khurais oilfield.

The Saudis lead a Western-backed military coalition supporting Yemen's government, in opposition to the Houthi rebel movement.

The attacks also come against a backdrop of continuing tension between the US and Iran, following US President Donald Trump's abandonment of a deal limiting Iran's nuclear activities and reinstatement of sanctions.

In a tweet, he said there was "no evidence" the drones came from Yemen.

He described the attack as "an unprecedented attack on the world's energy supply".

"We call on all nations to publicly and unequivocally condemn Iran's attacks," Pompeo added.

The US would work with its allies to ensure energy markets remained well supplied and "Iran is held accountable for its aggression", he added.

Trump authorized the use of the U.S. emergency oil stockpile to ensure stable supplies after the attack, which shut 5% of world production and sent crude prices soaring more than 19% in early trade on Monday, before moderating to show a 10% gain.

The White House said Trump had offered US support to help Saudi Arabia defend itself.